This invention relates generally to a process for preparing aluminoxanes and more specifically to the preparation of aluminoxanes, such as methylaluminoxane, by reacting a hydrocarbyl aluminum compound with a hydrate of an alkali metal halide such as lithium bromide dihydrate.
Vandenberg U.S. Pat. No. 3,219,591 reported the catalytic activity of compounds formed by the reaction of trialkyl aluminum with limited amounts of water in the polymerization of epichlorohydrin and other oxiranes. Shortly thereafter, Manyik, et al. U.S. Pat. No. 3,242,099 reported the use of aluminoxanes, made by reacting 0.85-1.05 moles of water with hydrocarbyl aluminum compounds such as triisobutylaluminum, as co-catalysts with certain transition metal compounds in the polymerization of monounsaturated .alpha.-olefins; e.g. ethylene and propylene. Isobutylaluminoxane was also made by adding an equal mole quantity of water to a heptane solution of triisobutylaluminum.
Manyik, et al. U.S. Pat. No. 3,300,458 prepare alkylaluminoxane by passing a hydrocarbon through water to form a wet hydrocarbon and mixing the wet hydrocarbon and an alkyl aluminum/hydrocarbon solution in a conduit.
Schoenthal, et al. U.S. Pat. No. 4,730,071 show the preparation of methyaluminoxane by dispersing water in toluene using an ultrasonic bath to cause the dispersion and then adding a toluene solution of trimethylaluminum to the dispersion. Schoenthal, et al. U.S. Pat. No. 4,730,072 is similar except it uses a high speed, high shear-inducing impeller to form the water dispersion.
Edwards, et al. U.S. Pat. No. 4,722,736 describe an aluminoxane process in which water is introduced below the surface of a solution of hydrocarbyl aluminum adjacent to a stirrer which serves to immediately disperse the water in the hydrocarbon solution.
The preparation of alkyl aluminoxanes from R.sub.2 AlOLi, formed by reacting AlR.sub.3 and anhydrous lithium hydroxide, and R.sub.2 AlCl has been reported in the literature, for example, Ueyama, et al., Inorganic Chemistry, 12, No. 10, 2218 (1972) and Aoyazi, et al., Inorganic Chemistry, 12, No. 11, 2702 (1973).
Sinn, et al. U.S. Pat. No. 4,404,344 prepare methylaluminoxane by adding trimethylaluminum to a slurry of CuSCO.sub.4 .multidot.5H.sub.2 O in toluene. Introducing water as a metal hydrate controls its reactivity with the trimethylaluminum. Kaminsky, et al. U.S. Pat. No. 4,544,762 is similar except it uses an aluminum sulfate salt hydrate to supply the water. Likewise, Welborn, et al. U.S. Pat. No. 4,665,208 describe the use of other metal salt hydrates such as FeSO.sub.4 .multidot.7H.sub.2 O as a water source in preparing aluminoxane. Kioka, et al. Japanese Patent Application 63-87717 discloses the use of hydrate salts which contain water of absorption or crystallization such as hydrated magnesium chloride, hydrated copper sulfate, hydrated ammonium sulfate, hydrated nickel sulfate and hydrated cerium III chloride.
A process has now been discovered for making hydrocarbylaluminoxanes using certain halide salt hydrates which greatly improves the recovery of aluminum values by permitting the use of lower reaction temperatures. Also, gel formation in aromatic solvents is avoided when preparing aluminoxanes from hydrocarbyl aluminum compounds where the alkyl groups have 2 or more carbon atoms, such as triethylaluminum, and triisobutylaluminum such that the products are easily filtered.